Smaller trucks, such as those commonly referred to as pick-up trucks, often have rear tailgates that move from a vertical closed position to a horizontal open position about a horizontal axis. Larger trucks, such as box trucks, semi-tractor trailers often have one or more rear doors that pivot vertically from open to closed positions. When in transit, these doors should normally be in a closed position to prevent cargo from sliding from or failing off of the truck. It is frequently difficult for an operator to see a truck's rear tailgate or cargo door because of the vehicle design or cargo that is blocking the view. A trailer being pulled by a truck cab may obstruct the operator's sight of doors on the rear of the trailer. What is needed is a better way to know what position tailgates, doors, and other objects on vehicles.